Veeam Backup and Replication defines retention as the number of restore points to keep for VMs within the job.
This is not measured by time, but the total number of “points” (files). It is important to keep the schedule of the job in mind when selecting the number of “points” to keep. See the following examples:
Also, with Backup Copy functionality, a GFS retention has become possible. See the GFS Retention section for details.